There are several systems used to control the raising and lowering of a window within a vehicle. One method uses a handle rotatably connected to a worm gear and a pinion gear. As the handle rotates, the gears operate as a pair to transmit and translate the turning force of the handle to a linear force that raises and lowers the window. The motion, speed, and position of the window are manually controlled by the user, which can provide a very precise control.
Unfortunately, manual control requires occupants to have the strength to raise or lower a window regardless of the handle's position. When multiple windows need to be adjusted, it can be difficult to raise and lower these windows unless the occupant is seated adjacent to each of the handles. This can be very difficult, especially when there is only one occupant and that occupant is driving.
Power windows have overcome some of these disadvantages by using electric motors to generate the turning and twisting forces needed to raise or lower a window. Power windows can be operated by pushing a toggle switch firmly down and then releasing it. Often, additional toggle switches are placed near the driver so that the driver can separately operate all of the vehicle's windows. In these systems, each passenger window is controlled by an independent switch. To raise or lower a specific window, a specific switch must be selected and then actuated.
While many power windows are easy to operate, they do not provide the precise control that some manual systems provide. To open a window to a desired position, for example, an occupant must push a window switch down. Once a desired position is reached, the occupant must release the switch. As the switch transitions from a closed to an open state, the window will continue to move until the switch is fully open. As a result, it can be difficult to control the position of a window precisely. Moreover, it can be difficult to control the position of multiple windows as each switch can have different transition periods.